Inverse PCR For use with Snyder mTn-lacZ/LEU2 based mutagenesis
Inverse PCR
I. Genomic DNA Prep
• from 5 ml culture, resuspend in 50 µl TE
II. Digestions
genomic DNA | 5 µl |
10x of appropriate NEB buffer | 5 µl |
0.5 µg/µl RNase | 1 µl |
H2O | 38 µl |
restriction enzyme | 1 µl |
• Use either AciI, AluI, HaeIII, HpaII, RsaI or TaqI for Leu transposon libraries
• 37 deg C/ >3 hours (or overnight)
• 65 deg C/ 20 min
III. Ligations (intramolecular, hopefully)
digested DNA | 10 µl |
10x ligation buffer | 20 µl |
H2O | ~170 µl |
T4 DNA ligase (NEB, 400U/µl) | 0.2 µl |
• all day at room temp or overnight at 4 deg C
• precipitate with 80 µl 5M NH4 Ac + ethanol…-20 deg C/ >1 hr; spin, dry, resuspend pellet in 100 µl TE
IV. PCR
ligated DNA | 10 µl |
3 M KCl | 0.75 µl |
1 M Tris, pH 8.5 | 0.4 µl |
25 mM MgCl2 | 3 µl |
10 mM dNTPs | 1 µl |
10 µM oligo#1* | 1 µl |
10 µM oligo#2* | 1 µl |
H2 O | 32.35 µl |
Taq (added after hot start) | 1 µl |
• 35 cycles of: 94 deg C/1', 62 deg C/1', 72 deg C/2'30"
*the choice of oligos used for the PCR reaction depends on what restriction enzyme was initially chosen to cut the genomic DNA and what "side" of the transposon you want to use as the starting point for the PCR.
Enzyme | Oligos for PCR |
AciI | InPCR3 and InPCR4 |
AluI | InPCR3 and InPCR4 |
HaeIII | InPCR3 and InPCR4 |
HpaII | InPCR3 and InPCR4 |
RsaI | InPCR1 and InPCR2 or InPCR4 and InPCR5 |
TaqI | InPCR1 and InPCR2 or InPCR4 and InPCR6 |
InPCR1 => 5'-taagttgggtaacgccagggttttc-3' InPCR2 => 5'-ttccatgttgccactcgctttaatg-3' InPCR3 => 5'-ataactacgatacgggagggcttacc-3' InPCR4 => 5'-gattaagcattggtaactgtcagacc-3' InPCR5 => 5'-cataattctcttactgtcatgccatcc-3' InPCR6 => 5'-tcaaggatcttaccgctgttgagatcc-3'
V. Cleanup for Sequencing (2 options)
1. Wizard PCR purification spin columns
• elute in 50 µl TE
OR:
2. Exonuclease I+ shrimp alkaline phosphatase treatment:
• In PCR tubes, add:
8.5 µl PCR product
1 µl Exonuclease I
1 µl SAP (shrimp alkaline phosphatase)
• 37 deg C/20 min
• 65 deg C/20 min
VI. Sequencing
cleaned DNA | 10.5 µl |
sequencing mix | 8 µl |
DMSO | 1 µl |
sequencing oligo �10 µM | 0.5µl |
• use Amersham cycle seq protocol (96 deg C/30", 45 deg C/15", 60 deg C/4'; 30 cycles for dilute templates)
• after cycling, put rxn through a Pharmacia Auto-Seq G-50 column, and dry
• if using the Exo/SAP treatment above, then just use the entire reaction for sequencing
• for sequencing from InPCR1-2 products, use mTn3-SEQ1 oligo
mTn3-SEQ1 => 5'-cccccttaacgtgagttttcgttccact-3'
• for sequencing from InPCR3-4, InPCR4-5, or InPCR4-6 products use mTn3-SEQ2 oligo
mTn3-SEQ2 => 5'-aaggatctaggtgaagatcc-3'